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    <title>Signal</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>Signal</b> -  Signal manual description</p>
    <h3>
      <font color="blue">Filters</font>
    </h3>
    <dl>
      <dd>
        <li>
          <b>
            <font color="maroon">analpf</font>
          </b>: analog low-pass filter</li>
        <li>
          <b>
            <font color="maroon">buttmag</font>
          </b>: squared magnitude response of a Butterworth filter</li>
        <li>
          <b>
            <font color="maroon">casc</font>
          </b>: creates cascade realization of filter</li>
        <li>
          <b>
            <font color="maroon">cheb1mag</font>
          </b>: square magnitude response of a type 1 Chebyshev filter</li>
        <li>
          <b>
            <font color="maroon">cheb2mag</font>
          </b>: square magnitude response of a type 1 Chebyshev filter</li>
        <li>
          <b>
            <font color="maroon">chepol</font>
          </b>: recursive implementation of Chebychev polynomial</li>
        <li>
          <b>
            <font color="maroon">convol</font>
          </b>: convolution of 2 discrete series</li>
        <li>
          <b>
            <font color="maroon">ell1 mag</font>
          </b>: squared magnitude of an elliptic filter</li>
        <li>
          <b>
            <font color="maroon">eqfir</font>
          </b>: minimax multi-band, linear phase, FIR filter</li>
        <li>
          <b>
            <font color="maroon">eqiir</font>
          </b>: design of iir filter</li>
        <li>
          <b>
            <font color="maroon">faurre</font>
          </b>: optimal lqg filter.</li>
        <li>
          <b>
            <font color="maroon">lindquis</font>
          </b>: optimal lqg filter lindquist algorithm</li>
        <li>
          <b>
            <font color="maroon">ffilt</font>
          </b>: FIR low-pass,high-pass, band-pass, or stop-band filter</li>
        <li>
          <b>
            <font color="maroon">filter</font>
          </b>: compute the filter model</li>
        <li>
          <b>
            <font color="maroon">find_freq</font>
          </b>: parameter compatibility for elliptic filter design</li>
        <li>
          <b>
            <font color="maroon">findm</font>
          </b>: for elliptic filter design</li>
        <li>
          <b>
            <font color="maroon">frmag</font>
          </b>: magnitude of the frequency responses of FIR and IIR filters.</li>
        <li>
          <b>
            <font color="maroon">fsfirlin</font>
          </b>: design of FIR, linear phase (frequency sampling technique)</li>
        <li>
          <b>
            <font color="maroon">fwiir</font>
          </b>: optimum design of IIR filters in cascade realization,</li>
        <li>
          <b>
            <font color="maroon">iir</font>
          </b>: designs an iir digital filter using analog filter designs.</li>
        <li>
          <b>
            <font color="maroon">iirgroup</font>
          </b>: group delay of iir filter</li>
        <li>
          <b>
            <font color="maroon">iirlp</font>
          </b>: Lp IIR filters optimization</li>
        <li>
          <b>
            <font color="maroon">group</font>
          </b>: calculate the group delay of a digital filter</li>
        <li>
          <b>
            <font color="maroon">optfir</font>
          </b>: optimal design of linear phase filters using linear programming</li>
        <li>
          <b>
            <font color="maroon">remezb</font>
          </b>: minimax approximation of a frequency domain magnitude response.</li>
        <li>
          <b>
            <font color="maroon">kalm</font>
          </b>: Kalman update and error variance</li>
        <li>
          <b>
            <font color="maroon">lev</font>
          </b>: resolve the Yule-Walker equations :</li>
        <li>
          <b>
            <font color="maroon">levin</font>
          </b>: solve recursively Toeplitz system (normal equations)</li>
        <li>
          <b>
            <font color="maroon">srfaur</font>
          </b>: square-root algorithm for the algebraic Riccati equation.</li>
        <li>
          <b>
            <font color="maroon">srkf</font>
          </b>: square-root Kalman filter algorithm</li>
        <li>
          <b>
            <font color="maroon">sskf</font>
          </b>: steady-state Kalman filter</li>
        <li>
          <b>
            <font color="maroon">system</font>
          </b>: generates the next observation given the old state</li>
        <li>
          <b>
            <font color="maroon">trans</font>
          </b>: transformation of standardized low-pass filter into low-pass, high-pass, band-pass, stop-band.</li>
        <li>
          <b>
            <font color="maroon">wfir</font>
          </b>: linear-phase windowed FIR low-pass, band-pass, high-pass, stop-band</li>
        <li>
          <b>
            <font color="maroon">wiener</font>
          </b>: Wiener estimate (forward-backward Kalman filter formulation)</li>
        <li>
          <b>
            <font color="maroon">wigner</font>
          </b>: time-frequency wigner spectrum of a signal.</li>
        <li>
          <b>
            <font color="maroon">window</font>
          </b>: calculate symmetric window</li>
        <li>
          <b>
            <font color="maroon">zpbutt</font>
          </b>: Butterworth analog filter</li>
        <li>
          <b>
            <font color="maroon">zpch1</font>
          </b>: poles of a type 1 Chebyshev analog filter</li>
        <li>
          <b>
            <font color="maroon">zpch2</font>
          </b>: poles and zeros of a type 2 Chebyshev analog filter</li>
        <li>
          <b>
            <font color="maroon">zpell</font>
          </b>: poles and zeros of prototype lowpass elliptic filter</li>
      </dd>
    </dl>
    <h3>
      <font color="blue">Spectral estimation</font>
    </h3>
    <dl>
      <dd>
        <li>
          <b>
            <font color="maroon">corr</font>
          </b>: correlation coefficients</li>
        <li>
          <b>
            <font color="maroon">cspect</font>
          </b>: spectral estimation using the modified periodogram method.</li>
        <li>
          <b>
            <font color="maroon">czt</font>
          </b>: chirp z-transform algorithm</li>
        <li>
          <b>
            <font color="maroon">intdec</font>
          </b>: change the sampling rate of a 1D or 2D signal</li>
        <li>
          <b>
            <font color="maroon">mese</font>
          </b>: calculate the maximum entropy spectral estimate</li>
        <li>
          <b>
            <font color="maroon">pspect</font>
          </b>: auto and cross-spectral estimate</li>
        <li>
          <b>
            <font color="maroon">wigner</font>
          </b>: Wigner-Ville time/frequency spectral estimation</li>
      </dd>
    </dl>
    <h3>
      <font color="blue">Transforms</font>
    </h3>
    <dl>
      <dd>
        <li>
          <b>
            <font color="maroon">dft</font>
          </b>: discrete Fourier transform</li>
        <li>
          <b>
            <font color="maroon">fft</font>
          </b>: fast flourier transform</li>
        <li>
          <b>
            <font color="maroon">hilb</font>
          </b>: Hilbert transform centred around the origin.</li>
        <li>
          <b>
            <font color="maroon">hank</font>
          </b>: hankel matrix of the covariance sequence of a vector process</li>
        <li>
          <b>
            <font color="maroon">mfft</font>
          </b>: fft for a multi-dimensional signal</li>
      </dd>
    </dl>
    <h3>
      <font color="blue">Identification</font>
    </h3>
    <dl>
      <dd>
        <li>
          <b>
            <font color="maroon">lattn,lattp</font>
          </b>: recursive solution of normal equations</li>
        <li>
          <b>
            <font color="maroon">phc</font>
          </b>: State space realisation by the principal hankel component  approximation method,</li>
        <li>
          <b>
            <font color="maroon">rpem</font>
          </b>: identification by the recursive prediction error method</li>
      </dd>
    </dl>
    <h3>
      <font color="blue">Miscellaneous</font>
    </h3>
    <dl>
      <dd>
        <li>
          <b>
            <font color="maroon">lgfft</font>
          </b>: computes p = ceil (log_2(x))</li>
        <li>
          <b>
            <font color="maroon">sinc</font>
          </b>: calculate the function sin(2*pi*fl*t)/(pi*t)</li>
        <li>
          <b>
            <font color="maroon">sincd</font>
          </b>: calculates the function Sin(N*x)/Sin(x)</li>
        <li>
          <b>
            <font color="maroon">%k</font>
          </b>: Jacobi's complete elliptic integral</li>
        <li>
          <b>
            <font color="maroon">%asn</font>
          </b>: .TP the elliptic integral :</li>
        <li>
          <b>
            <font color="maroon">%sn</font>
          </b>: Jacobi 's elliptic function with parameter m</li>
        <li>
          <b>
            <font color="maroon">bilt</font>
          </b>: bilinear transform or biquadratic transform.</li>
        <li>
          <b>
            <font color="maroon">jmat</font>
          </b>: permutes block rows or block columns of a matrix</li>
      </dd>
    </dl>
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